Best answer by Nancy_OVO
Sorry to hear about this. It sounds like there may be air pockets in your gas pipe that need bleeding out. They can be introduced into the pipework when a system that hasn't been touched in a very long time has some work done to it. In this case, this would be your smart meter exchange.
A Gas Safe Engineer will be able to do this for you. As the issue is affecting the gas supply beyond the meter itself, unfortunately we're not able to carry out any work on this. Have a look here for a good gas safe engineer: https://www.gassaferegister.co.uk/